To realize effective use of a frequency in satellite communication, there has been proposed a relay satellite mounted with a digital channelizer that relays data from a plurality of uplink beams to a plurality of downlink beams. A technology concerning the relay satellite mounted with the digital channelizer is disclosed in Patent Literature 1.
The digital channelizer disclosed in Patent Literature 1 receives uplink signals from beam areas in a plurality of ports and thereafter demultiplexes the uplink signals in a unit of a sub-channel. A route of demultiplexed signals is set through a switch. The demultiplexed signals are input to a multiplexing unit corresponding to ports at transmission destinations. A multiplexed signal is transmitted from a plurality of ports as a downlink signal. The power consumption of the digital channelizer increases in proportion to the number of ports. A technology for solving this problem is disclosed in Patent Literature 2.
Patent Literature 2 mentions that uplink signals from a plurality of beam areas are collectively analog/digital-converted after being multiplexed to reduce the number of A/D converters and attain a reduction in power consumption.
Non Patent Literature 1 discloses, as a demultiplexing and multiplexing system, a proposal of a system in which a polyphase filter and FFT (or IFFT) are used.